Ingot buggy drive



Feb. 21, 1961 Filed Jan. 5, 1954 G. FOX

INGOT BUGGY DRIVE 4 Sheets-Sheet 1 GORDON FOX T Q. 6m

Feb. 21, 1961 G. FOX 2,972,312

INGOT BUGGY DRIVE Filed Jan. 5, 1954 4 Sheets-Sheet 2 4i IL L i /T/ MI 5 21L /2\ w w fififi CONTROL 45 m 46 /6 FIELD 47 a: 250 v ac. VF, IR] A; 2150 u ac.

RX! F54 A m2 m2 NEQ -II IHW g: J PO91, F X IS 4 B p p ggyg -I r-. PM

F5 155 6 m5 IFE} i FIX? 55 ACC/ 26 FIELD 5 D t 050 FX 3 12x5 bffHF fl-o /M FIELD 2M FIELD 55 W M26 52/ B22 56H g m m PFD 5 l PRV6 INVENTOR. GORDON FOX his INGOT BUGGY DRIVE Gordon Fox, Chicago, Ill.,' assignor to Koppers Company,

' 1 Inc., a corporation of Delaware Filed Jan. 5, 1954, $81. No. 402,391

2 Claims. c1.1o4-17s 2,972,312 andis -v. 1196 "ice a drive and control system which places minimum dependence, for its action,'upon an operator.

Another feature of the present invention is to provide a drive system that permits the use of winches located remotely from the ingot buggy line of travel.

Another feature of the present invention is to provide a drive system that is efficient in its operation and economical in its maintenance.

Still another feature of the present invention is to provide a drive system which avoids acceleration of an ingot buggy to high speeds when the buggy is near the limits termed soaking pits. A number of these pits are spaced .in,,a row at regular intervals along the length of the soaking pit building; An ingot buggy or car runs alonga track extending along one side of the row of these pits. Heated-ingots, removed from the pits, are placed on the wingot buggy by an overhead crane and are transported from the respective pits to the mill.

1 In 1116. prior art, various types of drives have been used for these ingot buggies. For example, electric motors l iave been mounted on the buggy, transmitting tractive ort; to-some portion; ;of the buggy wheels. h s :seneral pe. of dri a n e en i i factory becauseof the inherent difliculties involved in -gthe operation and maintenance 'of required conductor rails and because of the limitations of tractive drive on only a portion of the buggy wheels. -been found undesirable to have the motor mounted on the buggy in close proximity to the handling of the hot -ingot.

In order to eliminate some of these difliculties, more Moreover, it has" of travel.

Numerous other features of the combined ingot buggy and drive system will become apparent from the description which follows.

More particularly, the present invention provides a transfer car drive system comprising a pair of spaced winches; a transfer car positioned between the winches; -a first cable having one end attached to one of the winches and its opposite end attached to the transfer car so as to pull on the transfer car in one direction; a second cable having one end attached to the other of the winches and its opposite end attached to the transfer car so as to pull on the transfer car in an opposite direction from the first cable pull; a winch drive mechanism for each of the winches; a pair of motors, each motor being adapted to drive one of the winches, through .the winch drive mechanism; a generator system adapted to supply electric power to the motors, and control means for the generator, system adapted to selectively govern the polarity and the relative votages. supplied by the generator system to the armatures ofthe respective motors; therechanges can be made in the arrangement, form, construcrecent ingot buggies have been driven by tow cables.

{The cables, attached to the head and tail end of the buggy have :beendriven from the same capstan or winch mechanism in response to the same motor drive. This has necessitatedthe, provision of a tunnel or its equivalent, generally under the ingot buggy track. The tail cable ;passes to thetail end of the track, assuming the operating winch to be located at the head end of the track. .-A take-up means has also been necessary to keep thecables reasonably taut in the event of cable stretch. Although this cable scheme provides rapid acceleration and de: -celeration of the buggy without whee-l slippage and further eliminates electrical conductors along the track- .qway, the provision of a tunnel under the ingot buggy track has proved to be undesirable.

present invention provides a means for retainin the advantages of the aforementioned cable drive. but

eliminates the need for a cable tunnel. I

k 7 One of the features of the present invention is to pro- 7 vide a drive system for an ingot buggy whereby ingots may be delivered to the millias fast as they can be ;processed, regardless of the length of the ingot buggy Ltravel..- L I A jndthei' feature of the present invention is to provide a' dri'v'e'system for an ingot buggy which permits close control and rapid spotting of the buggy.

tion and type of the elements disclosed without departing from the scope or spirit of this invention.

' Reference will now be made to the accompanyu'ng drawings which illustrate and exemplify an elementary embodiment of the apparatus of the invention in a preferred type of construction.

Figure 1 represents a schematic drawing of' the arrangement and drive system of an ingot buggy which connects the soaking pits with the blooming or slabbing mill. Figure 2 represents an electrical diagram for the ingot buggy drive system. For convenience, this figure is divided into three parts, indicated as Figure 2, part .A;

Figure 2, part B; and Figure 2, part C.

Referring to Figure l of the drawings; an ingot buggy track 10 is disclosed as positioned along one side of a row of spaced soaking pits, 1 to 6. The track 10 connects the soaking pits with a mill 11. Positioned on the track 10 is an ingot buggy 12. Connected to the tail end of the buggy is one end of a cable 14. The other end of this cable is connected to a winch 20. Connected to the head end of the-buggy is one end of a cable 16, the other h end of this passes over snatch block 17 or deflector sheave .'.Another feature of the present invention is to provide a easter ies? warm s ii y t a is t was and is connected to a winch 18. The deflector sheave permits the winch to be remotely located while still preserving cable pulls. in opposition, substantially in line with the tracks. It is to be understood that such sheaves can be used with both winches if so desired. The winch 20 is driven by a motor 2M through'winch drive gearing arrangement 24. The winch 18 is driven by a motor 1M through winch drive gearing arrangement 22.

The winch 18 is'further provided with twolimit switch cam mechanisms through a gearing arrangement 30. It is to be understood that in another embodiment ,of this invention thelirnitswitch cam mechanisms can be mounted on-the winch ztlinstead. Qne of these. limit agemgsra switch cam mechanisms is designated VLS and represents a vernier limit switch cam mechanism. The other limit switch is designated SLS and represents a selective limit switch cam mechanism. Itis to be further'understood that limit switch mechanisms other than ofthe'cam t'ype'can also be used with the present invention.

When'the heateddngots'are taken from the "first pit, nearest the mill, the ingot buggy movement is short. When the heated ingots are taken from remote pits, the ingo-t buggy movement is greater. In order to keep pace with the mill, ingots must be delivered as rapidly as the mill can process them, regardless of the length of the ingot buggy travel. To have adequate capacity when serving remote pits, the speedof the buggy'must be high (such as 800 feet per minute), while'when serving'closepits, the speed can-be law (such as' 400 feet per minute).

' the distance between center'lines ofadjacent pits, permitting a'ccuratemovement of the buggy, the'contacts effecting slow-down, and the stopping operations. Broadly, the cam mechanism SLS merely designates which of the pits the car-is'to stop before. This designation need be only rough, since the vernier limit switch VLS governs "accurate slow-down and stop functions.

' It is to be noted,' 'thatsince the distance from the first :j pit" to themillis usuallynot the'same as the'distance "frompittopit, separate cams on the vernier limit switch are necessary to provide for automatic slow -down'and stopping of the car at the mill. This vernier action is effective only when the car isat or near its terminal position at the mill and is of no effect at regularly-spaced intervals alongthe track relating to'the mill terminal position, corresponding to complete rotations of the vernier limit switch. It is further to be notedthat the vernier cams can be arranged and adjusted in accordance with the distance from pit to-pit and 'in 'accordance with the distance from pit number lto the mill.

" In operation, movement of the'ingot buggy iscontrolled by an operator positioned in a pulpitadjacent to the point of delivery of the ingots fro-m the buggy to the receiving table inadvance of the mill. {Since'thisposition is located 'a' considerable"distance' from the-pits, accurate spotting of the car is made possibleby an electrical control system for'the motors 1M 'and'ZM ineluding a selector switch shown as SS1, SS2, SS3, SS4,

SS5, SS6, in Fig.'2,'part C, a mill push 'button,'-"designated Mill, a Stop button, a pit push button,'designated Pit, a plurality of relays and their contacts and the contacts of the vernier limit switch cam mechanism and selector limit switch cam mechanism. In general, the selector switch,'SS, can be set for movement of theingot buggy to any one of the pits 1, 2, 3', *4, 5, or6. 'The- Mill push button can be set for movement of the ingot buggy to themill and the Pit push button can be set for movement of the ingot buggy to or between pits, in'both directions.

In a typical operation, the selector switch SS is set for the pit to whichthe ingot buggy is to be moved, then at intermediate speed. I This is effected by the different -'cams' on the "-aforede's'cribed vernier limit switch cam mechanism, VLS. Movements at fastspeed are restricted, in the instance described, to trips from the mill to remote pits 4, 5 or 6 and to trips from pits 4, 5 and 6 to the mill. Movements between the mill and pits 1, 2 and 3 are made at intermediate speed. Movements from one pit to another, which occur only occasionally, are made at intermediate speed; For a given movement, one winch with its motor pulls the car alongthe track and the other winchwith its motor holds back against the car movement, keeping both cables fairly taut. The'rlative rope pulls of the respective driving and dragging motors is controlled to cause acceleration'or deceleration. This control is done by' controlling the applied voltages, counter voltages, and armature currents of the respective driving motors through the aforementioned control system which is described in detail below. This control system is represented in Figure 2 of the drawings "and, for the purposes of clarity, a statement of the significance of the numerals and letterings usedth'ereinfis motor and correspondingly contributes to a drag effect I of the other motor.

The letters DEC (line'63) refer to a decelerating relay "coil which actslike relay coil ACC to' effect a local circulating current but of reduced value as compared-with that set up by relay coil ACC. In combinationwiththe falling olf of the'volt-ageof generator 'lGjit'catises decelerati'on.

The letters 1F and 2F- (line '59)] refer-to forwarddir'ectional relay 'coils. "The principal*"funct ion' of "these relaycoils -is to orient the polarity of'-gerierator1G; in

order to govern'the direction of "movement.

The letters-1R and 2K (line 61) refer 'toiieve'rse dh rectional relay coils, functioning inversely 'to"1F-'andf2*F.

The letters FS (line' '65) refer to a fast "speed relay coil. The principal function of this relay coil i's'to maiti- *mize the 'stength of the reference fieldofgener'ator'exciter GE, thereby causing generator 16 to develop-a relatively high voltage, res'ultingin high speed operation of motors 1M and 2M. e

Fhe letters FX (line 58) 'refer to-"anauxihary relay 'coil which-functions asa-directional relay "coil for the "iield of generator-2G.

;-The letters RX (line 60) refer to"an'auxiliaryrelay coil functioning inversely-of FX. H

Theletters lMl-andZMl (lines 41 -43) refer to con- "tacts which rearrange the armature'ci'rcuits of motOrs lM 'a nd 2M, connecting one or the other'directlyacross the generator lG. v I

The letters lTl' 'and 2T1 '(lines 41-43) refer-tofcontacts which selectively introduce generator ZG-into' boost- "ing relationship with respect to motors IM or 2M.

' The letters BRl and BR2 (line 56) refer to coils which are connected with brakes for the winch drives. When these coils are energized, the brakes which are holding 3 r the winch drivesare released.

The letters MR linens ire fer ft tr verse relay coil. This coil sets up circuits which cau'sefmovement of the ingot buggy toward themill tobecontinued until the mill is reached.

The letters MRF (line 66) refer to amill fastrelaycoil. This relay coil acts to insure that certain movementsof theingot buggy toward the (namely, from pits 4, 5

" and 6) will be at fast speed.

The letters 'MRI (line 66) referto' a mill'intermediate speed relay coil. This coil acts to insure thatdertain movements of the ingot buggy toward the mill, {namely "from pits number 1, 2"and'3) will be at'intermedizite speed.

e lettersistline 64were;tannins-m" ed iat' 'speed relay coil. This coil functions to moderate the strength .,.of the GE Reference Field, thereby causing generator 1 G to develop an intermediate voltage, resulting in inter mediate speed of movement of the ingot buggy.

The letters PFD (line 68) refer to a pit (forward) relay coil. This coil sets up a circuit which leads to movement in a forward direction (away from the mill).

The letters PRV (line 69) represent a pit reverse relay coil. This coil sets up a circuit which leads to movements between pits (toward the mill).

The letters PFF (line 67) referto a pit forward fast relay coil. This coil acts to insure fast movement from the mill to pits numbers 4, 5 and 6. I The letters PFX (line 70) refer to a pit forward auxiliary relay coil. This coil acts to cause the coil PFF to energize on trips starting from the mill to pits numbers 4, 5 and 6.

It'also acts to cause relay coil PFI to energize for trips from one pit to another in the forward direction (from the mill) The letters PRI (line 67) refer to a pit reverse intermediate relay coil. This coil causes movements between pits toward the mill to take place at intermediate speed.

The letters UV refer to an undervoltage relay coil. For the purposes of uniformity in the electrical diagram of Fig. 2, contacts biased to open position are indicated by vertical parallel lines, and contacts biased to closed position are indicated by vertical parallel lines with a diagonal line therethrough;

In general, the contacts are identified by the characters applied to their operating relay coils, the contacts being differentiated by the addition of sulfixes. For example, relaycoil 1F (line 59) controls the contacts 1F1, 1F2.an.d 1P3 (line 51).

Referring to Figure 2 of the drawings, line 44 contains I generator 16 which applies to basic power to drive the two winch drive motors, 1M and 2M.

Line 41 which extends across the main generator 16 includes the contact 1M1 (normally biased to open) and the motor 1M in series therewith. In parallel with the contact 1M1 is the booster generator 2G and the contact 2T1 (normally biased to open) in series with this booster designated GE.

Line 51 extends from the positive side of a 250 volt D.C. line, designated POS (other voltages can be used) through the contact RX1 (normally biased to open), the contact PS4 (normally biased to open), the resistance unit A, the contact 1F2 (normally biased to open), the

contact 1R2 (normally biased to open) to the negative side of the line, designated NEG. In parallel with the contact RX1, is the contact FXI (normally biased to open). In parallel with the contact PS4 and resistance unit A is the contact 184 (normally biased'to open) and v the resistance unit B in series therewith. Contact 1.94 and resistance unit B are also in series with contact FXl. Also in parallel with the contact F54 and resistance unit A is the contact FS5 (normally biased to closed), the contact 185 in series therewith (normally biased to closed) and the resistance unit C in series therewith. In parallel H with the contact 1F2 and the contact 1R2 in series therewith, are the contacts 1R3 (normally biased to open) and 1P3 (norm-ally biased to open) in series therewith. These latter two contacts are also in series with resistance unit C. Connected to the line which connects the coniitacts 1F2 and 1R2 is one side of the generator exciter' GE (line 47 through the contact 1F1. (normallybiased to;

closed). Connected to the .line which connects contacts IRS and 1P3 isthe other side of the'gener'ator exciter GE (line 47) through the contact 1R1(no'rmally biasedto closed). One end of the GE Reference Field is connected to the line which connects contacts 1P2 and 1R2. The other end of the line of theGE Reference Fieldis' connected to the line connecting the contacts IRS and IFS.

Line 52 extends from POS through contact RX2 ('normally biased to open), through contact FX2 (normally biased to open) to NEG. I 1

Line 53 extends from POS through contactFXS :(normally biased to open),.contact RX3 (normally biased to i open) toNEG.

Extending across lines 52 and'53 is a line which includes the variable resistance unit E, the variable resistance ui it D, and the field of generator 2G," all in series. Qneehd of this line is connected intermediate thecontatitsjlRXZ and FX2 (line 52), and the other end of this isco'nn'ect'ed intermediate the contacts FX3 and RXIl (line'53); ii-In series with the adjustment arm of resistance unit Df'and parallel with resistance unit E is the contact ACCI normally biased to open). In series with the adjustment arm biased to open).

of the resistance unit E is the contact DECllnormally Line 54 extends from POS through 1M field to Line 55 extends from POS'through2M field to NEG. Line 56 extends from POS through oontact M R6 (normally biased to open), relay coil 'BRI' nann sen BR2 to NEG. In parallel with contact MR6 are contacts PFDS (normally biased toopen) "and contact PRV6 (normally biased to open). i Positioned between lines 56 and 57 in both POS and NEG line are-the fuses'F which protect 'the remainder pf the control equipment thereafter.

Line 57 extends from POS through-the contact (normally biased to open) of theRe'setbutton, through the Protective Devices in seriestherewith (not shown), and the undervoltage relay coil UV to NEG." -In parallel with the reset button is contact UV1 (normally biased toopen).

biased to open) connects the'line'designated POS to the line designated POS. v Line 58 extends from POS throughcontact PFDl (normally biased to open), contact 2M2 (normally biased to closed) in series therewith, and relay coil 1M in series therewith to NEG. In parallel with relay coil 1M are the relay coils FX and 1T. 7 i 3 Line 59 extends from POS through contact PF;F1 (normally biased to open), the contact 1M2 (normally biased to open) in series therewith, contact 2R1 (normally biased to closed) in series therewith, and relay coil IP in series therewith to NEG. In parallel with the contact PFFI is the contact PFIl (normally biased to open). In parallel with relay coil 1F, is relay coil 2F.

Extending across lines 58 and 59, is a line which contains the contact VLSl. One end of this line is connected to the line connecting contacts PFDI' and 2M2, and the other end of this line is connected to the 'line connecting the contacts PFFl and 1M2.-' Line 60'extends from POS through contact PR V1 (normally biased to open), the contact 1M3 (normally biased to closed) and the. relay coil RX to NEG. In parallel with the relay coil RX are the relay coils 2M and 2T. In parallel with the contact PRVl is* tl 1e-' contact MR1 (normally'biased'to open).- Line 61 extends from POS through the contact lyflhll (normally biased to open), through the contact 2M3 (normally biased to open) in series therewith, through the contact 2P1 (normally biasedto' closed), through-"the relay coil 2R in series therewith,-to- NEG; In parallel with relay coil 2R is therelay coil --1R.- -;In1parallel with the contact MRI1 are the contacts MRF1 (norm ally biased to open) and PRIl (normally biased to open). Extending across the line 60 and61 is aline .which-contains the Contact UV1 in series with contact 'UV2 (normally y rnally biased to closed).

' 'ignated PO S with a linedesignated POS.

aie'ra'aia fseries therewith. Tone "end a this line 'is' connected to f theline'whichconnectscontacts PRVl and 1M3, the

other end of this'lineis connected to the line which coniiects; contacts MRIl'and 2M3. These contacts PRVZ nected contacts MR2 (normally"bi'ased to open) "and Line 62' extends nsm'roswhieagii contact 182 '(normally biased to; open) and the relay coil ACC' inseries 'jtherewithto NEG. Inparallel'with the contact 182 is 11 c contact PS2 (normally biasd'to open).

Line 63 extehds admires" through Contact 183 '(normally biased to nosed "contact PS3 (normally "biased to closed) in'sei'ies therewith, and the relay coil DEC ill'ser'ies therewith :toNEG.

Line 64 extends from'POS' through the contact PRI2 (nor-mally biased to open),"the contact FS6 (normally biased to closed)in"s eries therewith, and the relay coil IS in series therewith to NEG. In parallel with the contact PFIZ and with each other are the contacts PRIZ (nor- "mally biased to open) and MRIZ (normally biased to lopem- PRV3, (norrnally biased to open) in series with the contact VLS4, and paralleling this arrangement is the contact 'PFDZ (normally biased to open) in series with the con- Paralleling this arrangement is the contact tact VLSSf. Parallelingthe line whichincludes the cont aCtS PFD Z and VLS5 is a'line which includes the contact MRS (normally'biased-to open) in'series with-the contact VLS6} i .v Line 65 extends from'POS' throughcontact MRF2 (normally biased to open), Fontact PF-I3 (normally biased to closed) in series therewith, contact-MRI3 (normally bl8d to closed) in series therewith, and relay coil FS in series therewith to NEG. In parallel with contact MRF2 is'the contact PFF2 (normally biased to open).v In parallel with-this arrangement is the contact MR3 (normally biased to open) in series with the contact .YLSS. In parallel with the line including the contacts MR3 and VLS8 is a line including'aforementioned contact PFDZ in series with contact VLS7.

Positioned in the positive line between lines 65 and 66,

in series therewith, is stop-button designated Stop (nor- This button connects line des- Line 66 extends from POS-through the Mill push button,'through contact PFD3 (normally biased to closed) i in'series therewith, through the contact PRV4 (normally biased to closed) in seriestherewith, through the contact ySL-S10 in series therewith, through the contact MR1-'3 (normally biased to closed) in series therewith, and,

through the relay coil MRI in series therewith, to NEG.

"In parallel with the Mill push button of line 66 are the contacts MRI4 (normally biased to open) and MRF6 (normally biased to open).

In parallel with contacts SL810, MRF3, and relay coil ;MRI in series," is another line containing contacts 2R2 -(normallybiased to open), MR4 (normally biased to open) in -s eries -therewith,- and relay coil MR in series therewith. Paralleling contacts 2R2 and MR4 are contacts MRFS (normally biased'to open) and MRIS (norrnally biased to open).

Paralleling the contact MRF3 and relay coil MRI is a line containing the contact SLSZtl-and the relay coil MRF.

"iParalleling the contact SLSZO is a' contact MRF4 (norfmally biasedto open).

" Line 67"extends'from PO through Pit button in fseries with contact MR5 (normally biased to closed), contacts SS1; SLSl, and relay coil PFI to NEG. Paralleling p thhtton 'are thefcontacts-PPM (normally biased to ""PRIS '(normally biased to open) "and-contact:

PFFS (normally biased to open). Paralleling' the-contacts'SSl and SLSI is'a line containing theseries connected contacts" SS2 and SLSZ. A second line containing the series connected contacts SS3 and SLS3 also parallels the contacts SS1 and SLSl. Paralleling the contact SLSI and relay coil PFI is a line containing the series connected contact SL811 and the relay coil PR1. Paralleling thecontact SLS2 and the relay coil is a line con- "taining the contacts'SL'S22'inseries with the relay coil PRI. Paralleling the contact SLS3 in series with the relay coil PFI is'aline containing the contact SL833 in series-with the relay coil PR1. Positioned in parallel with the contacts SSL'SLSI, and the relay coil PFI is a line containing the contact SS4, in series with the contact SLS4, PFX2 (normally'biased to open), and the relay coil PFF. The contact PFX2 is paralleled by a' the contact PFX2 and relay coil PFF is a line containing the series connected contact SL855 and the relay coil PRI.

Also positioned in parallel with the series connected contacts SS4 and SLS4' is a line containing the series connected contacts'SSG and SLS6.

Positioned inparallel with the contacts SLS6, PFX2 and relay coil PFF is a line containing the series connected contact SL866 and relay coil PR1.

Line 68 runs from POS through the contact PFF6 (normally biased to open),'the relay coil PFD to NEG. Positioned in parallel with the contact PFF6 is the contact PFIS (normally biased to open). Also positioned in parallel with the contact PFF6 is a line containing the series connected contacts 2P2 and PFD4 (normally biased to open).

Line 69 extends from POS" through contact 2R3 (normally biased to open), through contact PRVS (normally biased to open), through relay coil PRV to NEG. Positioned in parallel with the contacts 2R3 and PRVS is the contact PRI4 (normally biased to open).

Line 70 runs from POS through the contact SL830, the relay coil PFX to NEG.

It is to be noted that Figures 2B and 2C further disclose broadly the cam developments for the vernier limit switch and selector limit switch, respectively,

It is'to be noted that the vernier limit switch rotates through 360 while the transfer car travels the distance from the center line of one pit to the center line'of an adjacent pit. Limit switch VLS makes about seven (7) revolutions during a complete travel from the mill to the opposite extremity of travel. Limit switch VLS rotates in one direction while the transfer car moves forward (away from mill) and in the other direction when the transfer car moves in reverse (toward the mill).

'VLS1'Signals stop at a soaking pit when traveling for- 'VLS5-Signals slow-down preparatory to stop at a soaking pit when traveling forward at intermediate speed. VLS6Signals slow-down preparatory to stop at the mill when traveling reverse at intermediate speed.

VLS7-Signalsslow-down preparatory to stop at a soaking pit when traveling torward at fastvspeed.

the mills or away from the mill.

" VLS8-Sig1ials slow-down preparatory to stop at the mill when traveling at fast speed. As can be seen from a study of the circuit disclosed in Figure 2 of the drawings, the motors 1M and 2M are supplied from two generators, namely, 16 and 2G. Gen- -erator 1G supplies adjustable voltage to the system as a whole. Generator 2G is a smaller generator which I supplies as supplementary or booster voltage. The power for the drive as a whole comes mainly from the generator 1G. The generator 2G simply supplies difierential voltage which causes a local flow of current through the motor armatures and the booster generator to cause one motor to tend to run faster than the other, thereby causing one to act as a driving unit and the other to act as a dragging unit.

The voltages of generator 1G and 2G are regulated bythe amount of their respective field excitations. The voltage of generator 1G is reversed to determine the general direction of movement of the ingot buggy toward Similarly, the voltage of 2G is reversed so that its action is properly related to the voltage of 16.

\For example, when generator 16 has its voltage reversed it is necessary also to reverse the generator voltage of 2G. This is accomplished by reversing the fields which excite generator 1G and simultaneously reversing booster voltage is made by means of contactors 1M1,

' 2T1, 1T1. and 2M1 as afore-described. Contactors 1M1 and.1T1 are closed for one direction of movement. and I contactors 2M1 and 2T1-are closed for the other direction of movement.

The field of generator 1G is excited through the exciter i GE positioned in line 47. This exciter is in turn excited in part by a reference field supplied from a 250 volt constant potential circuit, designated in the drawing as -POS-NEG, and in part by another field which is connected across generator 1G, responding to the voltage thereof. The control field responsive to generator 1G is in opposition to the reference field supplied from the 250 volt circuit. The speed of operation of the ingot-buggy is determined primarily by the voltage developed bygeneratOrIG. By controlling. the amount of resistance connected in'series with the reference field of exciter GE, the voltage of 'the generator 16 can be controlled.

In. line 51 the several resistance units A, B and C are each provided with the contacts F54, I84, and the contacts PS5 and 155 respectively. Dependent upon which of these contacts is open and which is closed, the resistance in circuit with the reference field is varied, and accordingly, the excitation of generator 1G is varied.

The movement speed of the ingot buggy is in accord with this change of voltage.

It has been noted that the directions of the fields must be reversed in order to reverse the direction of movement of the ingot buggy. The fields of the exciter GE are reversed by means of contacts IE2 and IE3 for one and R X3 for one direction of movement, and contacts FXZ and FX3 for the other direction of movement. The

existence of the reference field is determined by the closure of either contacts RXl or FXl as the case may be. When both of these contacts are open the reference 1 I field is not conne cted across the 250 volt system. How'- a low voltage.

ever, there might be a little residual magnetismin, the

poles of this exciter, causing it to set up some excitation in the field 1G and thereby causing 1G to generate at This voltage is killed by short circuiting of the reference field of GE across its own armature. The direction of flow of current in the reference field opposes the voltage of exciter GE, causing a suicide efiect.

The amount of boosting effect of generator 2G is determined by its field strength. This in turn is influenced by the amount of resistance in circuit with the field, and

this in turn is determined by the open or closed position of contacts ACCl or DECl (lines 52 and 53).

The brakes applied to the motors 1M and 2M, are controlled by the relay coils BR1 and BRZ, respectively, through any one of three contacts MR6, PFDS and PRV6 (line 56). When movement is toward the mill and is destined to go all the way to the mill, the brakes are controlled through contact MR6. When the movement is to be made in the direction of the mill from one pit to another pit, the brakes are controlled through contact PRV6. When the movement is in a direction away from the mill, the brakes are controlled through contact PFDS.

In order to describe the operation of the circuit for Figure 2 more completely the sequence of operation in this circuit is described for five dififerent. movements of the ingot buggy as follows:

(1) Movement of the ingot buggy from pit 4 to the mill.

(2) Movement of the ingot buggy from pit 3 to the mill.

(3) Movement of the ingot buggy from the mill to pit 4.

(4) Movement of the ingot buggy from pit 4 to pit 2.

(5) Movement of the ingot buggy from pit 1 to pit-5.

Sequence of trip from pit 4 to the mill Assume the undervoltage relay coil UV in line 57 to be energized. Contacts UV1 and UV2 are thus closed.

.tacts MR1, 1M3, and relays RX, 2M and 2T to NEG (line 60).

It is to be noted further that the energization of coils MRF and 2M completes the circuit from POS, through contacts MRFl, 2M3, 2F1 and coils IR and 2R (line 61).

-The actuation of coil 2R completes the holding circuit for coil MR through contacts 2R2 and MR4 (line 66).

' Actuation of coils 2M and 2T establishes the relation of generator 2G to boost the voltage applied to the motor 1M by closing the contacts 2M1 and 2T1. The actuation of coil 1R causes the contacts 1R2 and 1R3 to establish a direction of the GE field, hence, the polarity of voltage 1G and direction of movement (toward the mill). The actuation of coil MR (above) energizes and releases brakes through the coils BR1 and BRZ (line 56). The actuation of coil RX (line 60), sets up the circuit (line 51) from POS through-contacts RXI, PS4, 1R3; GE Reference Field and 1R2 to NEG, starting the voltage buildup in generator 16. It further establishes the circuit (line 52) through contacts RX2, 2G field and RX3 determining the booster voltage polarity (lines 52 and 53). The energization of coil MRF (line 66) also energizes coil FS (line 65) through the contacts MRFZ. This causes closure of contacts PS4. This also closes contacts F82 (line 62) causing the relay coil ACC to be energized. Closure of contacts ACCl (lines 52 and 53) boosts the voltage of generator 2G and increases the difierential rope pull since motor 1M has more voltage impressed on it than motor number 2M, hencelMacts as a motor and 2M tends to act as a generator or liorm a holding circuit.

I and 2F, thereby actuating these coils.

of coil 2F completes the holding circuit for the coil PFD drag. The voltage ofgenerator 1G builds up,increas- This'field opposes the reference'field and limits the voltage of generator 1G. Becauseof the small resistance in the circuit of'FS4, theeftect of the GE Reference Field ismaximum and therefore maximum motor speed is obtained as a result of the maximum voltage developed by generator 1G. As the buggy travels toward the mill, the limit switch contact-VLS3 (lines 60 and 61) is opened at spaced intervals, but no effectresults because it is -covered by the contact MRFI (line 61). I

When the buggy approaches close to the mill the limit contact SL810 (line 66) opens, thereby deenergizing the coil MRF. This would result inthe deenergization-of the coil FS (line 65) because of the opening of contact MRFZ, except for covering circuits, through'MR3 and VLSS. When the VLSS contact is opened in due course, coil FS is deenergized. The deenergization of coil FS opens contact PS4 (line51) and closes contact FSS, causing voltage of generator 1G to decrease. The opening of contact FS2. (line 62) and closure of PS3 (line 63) deenergizes coil ACC and energizes coil DEC, decreasing diflerential pull of motor 1M in comparison with motor 2M, facilitating deceleration. The speed of the ingot buggy drops to a slow or creeping value.

Final stop is effected when limit contact VLS3 opens. This occurs since the cover circuit through MRFI (line 61) is now open. This results in the deenergization of coils IR and 2R, killing the voltage of the exciter GE. The deenergization of coil 2R further causes the con- The opening of contact MR6 (line 56) releases the brakes.

Sequence of trip from pit 3 to the mill If the buggy has started toward the mill from pit 3 instead of pit 4, the limit contact SL820 (line 66) would have been ineffective, hence the coil MRI wouldhave been actuated instead of the coil MRF. The sequence of events would then be the same except contacts would be responsive to the coil MRI instead of responsive to the coil MRF. The coil FS (line 65) would not be energized because of open contact MRI3 and the coil IS (line 64) would be energized instead, contacts MRIZ and F86 being closed. The closure of contact 1S4 (line 51) would limit the voltage of generator 1G to a lower value, anda lesser running speed would result.

- PFX is energized through the contact SL830 (line 70).

The selector switch is then set bythe operator to close the contact SS4 (line 67). Upon pushing the Pit button (line67), the circuit through contacts MR5, SS4, SLS4, PFXZ and through the coil PFF is complete to NEG. Actuation of the coil P FF closes the contact PFFS to The -Pit button is shunted by the contact PFFS which is closed by actuation of this coil.

Theclosure of contact PFF'G (line 68) completes the circuit through'the coil PFD and energizes the same. This results in a closure of the contact P-FDI (line 58),

leading to the energization of coils FX, 1M and 1T.

The closure of contact P'FFI (line 59) as a result of the energization of the coil PFF, completes the circuit through contacts 1M2, 2R1 and through the coils l F The energization (line-68) by closing the contact 2P2. Energization of coils 1M and IT (line 53) establishes the relationship of the generator 26 to boost the voltage applied to motor 2M.

direction of exciterGE Reference Field through the con- 'tacts 1F2'and 1P3, hence the. polarity of voltage 1G and the direction of movement away from the mill (forward).

The energization of coil PFD (line 68) as aforedescribed causes the brakes to be released through coils BR1 and BR2'by closing the contact PFDS (line 56). "The energization'of coil FX (line 58) sets up the circuit 'from'POS (line 51) through the contacts FXI, 1P2, the GE Reference Field, 1F3, to NEG. The energization of this coil FX further establishes the circuit through the contacts FX2 and FX3, determining the booster voltage PS4, completing the circuit for the GE Reference Field,

causing voltage to build up in generator 1G. This also in turn causes the contact PS2 (line 62) to be closed thereby energizing the coil ACC.

Contact ACCl (lines 52-53) is closed and the voltage of generator 2G is boosted, establishing a tendency for the motor 2M to act as a motor and the motor IM to act as a generator or a drag. The voltage build up of generator 16 is determined by the closure of contact PS4 and the opening of contact PS5 and is maximum. High running speed results. As the buggy travels away from the mill, limit switch contactVLSl (lines 58-59) is opened at spaced intervals but there is no efiect because contact PFFI acting as a cover'is closed.

-Whenthe buggy approaches pit 4, limit contact SLS4 (line 67 opens, thereby deenergizing the coil PFF. This would result in a deenergization of the coil FS (line 65) because of the opening of contact PFFZ but this does not take place due to the cover circuit through the closed contacts PFD2 and VLS7. When the contact VLS7 is opened in due course, the coil FS is then deenergized.

The deenergization of coil FS opens the contact FS4 (line 51) and closes contact PS5, causing the voltage of generator 16 to decrease. Opening contact FS2 (line 62) deenergizes the coil ACC, closure of contact PS3 (line 63) causes the coil DEC to be energized, affecting the differential pulls of motors 1M and 2M, encouraging deceleration. The speed of the buggy drops to a low value.

The final stop is effected when the limit contact VLS1 opens, the cover circuit through PFF1 (line 59) being now open. This results in deenergizing 1F and 2F (line 59), killing the voltage to the exciter GE (line 47). The deenergization of coil 2F (line 59) causes coil PFD (line 68) to be energized since the contact 2F2 has been opened. It is to be noted that coil PFF has already been deenergized. The opening of contact PFDS (line 56) causes a setting of the brakes through relay coils BRl and BR2 which are deenergized.

Trip from pit 4 to pit 2 PRV1 and 1M3. Closure of contact PRIl (line 61) completes the circuit from POS through contacts 2M3, 2F1 and relays IR and 2R to NEG. The energization of coil 2R completes the holding circuit for the coil PRV (line 69) through closed contacts 2R3 and PRV5.

The energization of relays 2M and 2T (line 60) establishes the relation of generator 2G to boost voltage applied to motor 1M, causing it to motor and 2M to drag."

: Energization of IR and 2R establishes the direction of the GE Reference Field, hence'the polarity of voltage 1G and the direction of movement of the ingot buggy (toward the mill).

The aforedescribed energization-ofcoil PRV (line .69)

closes the contact PRV6 (line 56) leading to the release of brakes through coils BRl and BR2. The energization of coil RX (line'60) sets up the circuit from POS through the contacts RXl (line 51), 1R3, the GE Reference Field, and the contact 1R2. The energization for this coil RX further establishes the circuit through the contact RX2 (line 52), 2G field, and contact RXS, determining the booster voltage polarity.

The energization of coil PRI (line 67) as aforedescribed causes the coil IS (line 64) to be energized through the contacts PR12 and PS6. This causes closure of contact 184 (line 51) completing the circuit for the GE Reference Field, causing the voltage to build up in generator 16. This also in turn causes the coil ACC (line 62) to be energized through the closed contact 182. The energization of ACC boosts the voltage of generator 26, causing the motor 1M to motor and motor 2M tend to drag.

As the buggy travels toward pit 2, the limit switch contact VLS2 is opened at spaced intervals but this has no efiect since it is covered by the closed contact PRIl (line 61). As the buggy comes close to pit number 2, limit switch contact SL822 opens, thereby deenergizing the coil PRI (line 67). This would result in the opening of coil IS (line 64) because of the opening of contact PRI2, however the circuit is covered through the closed contacts PRV3 and VLS4. When contact VLS4 is open on arrival near the pit 2, in due course, the coil IS is then deenergized.

The deenergization of coil IS opens contact 1S4 (lines 51-52) and closes contact 185, causing the voltage of generator 16 to decrease. The opening of contact IS2 and closure of contact 183 causes the coil ACC (line 62) to be deenergized and coil DEC (line 63) to be energized, thereby modifying the motor action of motor 1M and the drag action of motor 2M. Deceleration is encouraged.

The final stop is effected when the limit contact VLS2 (lines 6061) is open, the cover circuit through PRIl now being open, thereby causing the coils IR and 2R to be deenergized and killing the voltage of exciter GB. The deenergization of coil 2R causes the coil PRV (line 69) to be deenergized because of the openings of contact 2R3, the contact PRI4 beign already opened. The opening of contact PRV6 (line 56) leads to the setting of the brakes through deenergization of coils BRl and 8R2.

Sequence of trip from pit 1 to pit Assume the buggy is at pit 1. The selector switch SS is set to close the contact SS5. The Pit button (line 67) is pushed closed and the circuit from POS" through MR5,

. SS5, SLSS, PFF4, and PFXl, and the coil PFI to NEG is completed. With the energization of coil PFI, the Pit button is shunted by the closed contact PFI4. Contact PFIS (line 68) is also caused to close and this leads to the energization of coil PFD. This in turn energizes the coils FX, 1M and IT, since the contacts PFDl (line 58) and 2M2 are closed.

The aforedescribed energization of coil PFI completes the circuit from POS' through PFIl (line 59) contacts 1M2 and 2R1 to energize the coils 1F and 2F. The energization of coil 2F completes the holding circuit for the coil PFD (line 68) through the closed contacts 2F2 and PFD4.

The energization of coils 1M and IT establishes the direction of the GE Reference Field, hence the polarity of voltage 16 and the direction of movement of the ingot buggy from the mill (forward).

The energization of coil PFD (line 68) closes contact PFDS (line 56) causing the brakes to be released through BR]. and BRZ. The aforedescribed energization of coil PX sets up the circuit from POS through contact FXl, 1P2, the GE Reference Field and 1P3.

The aforedescribed energization of coil FX establishes a circuit through FXd, 2G field and FXZ, determining the booster voltage polarity.

The energization of coil PFI (line 67) energizes the. coil IS (line 64) through the contacts PFI2 and PS4. This causes closure of contact 184 (line 51) completing the circuit for the GE Reference Field, causing the voltage to build up in generator 1G. This also in turn energizes the coil ACC (line 62) through the contact 182. The energization of coil ACC boosts the voltage of generator 26 causing the motor 2M to motor and motor 1M tend to drag. I

As the buggy travels toward pit 5, the limit switch contact VLS1 (lines 58-59) is open at spaced intervals, but this has no effect since it is covered by the closed contact PFIl (line 59).

As the buggy comes close to pit 5, the limit switch contact SLSS opens, thereby deenergizing the coil PFI (line 67 This would result in the deenergizing of the coil IS because of the opening of the contact PFI2 '(line 64), however, the circuit is covered through theclosed contacts PFD2 and VLSS. When the contact VLSS is opened on approach of .the ingot buggy to pit 5 in due course, the coil IS is deenergized. The deenergization of this coil opens the contact 184 (line 51) and closes the contact 185, causing the voltage of generator 1G to decrease. The opening of contact 182 and closure of contact 183 causes the coil ACC (line 62) to deenergize and the coil DEC (line 63) to energize, thereby modifying motor action of motor 1M. Deceleration is encouraged.

The final stop is effected when the limit contact VLS1 (lines 58-59) opens, the cover circuit through contact PFIl (line 59) now being open, thereby the coils 1F and 2F (line 59) are deenergized, killing the voltage on the exciter GB.

The deenergization of coil 2F causes the coil PFD (line 68) to be deenergized since the contacts 2P2 and PFIS are open. This in turn opens the contact PFDS (line 56), leading to the setting of brakes through deenergized coils BRl and BR2.

From the five aforedescribed movements of the ingot buggy it should now be apparent to one skilled'in the art .that the operator can control various other movements of this buggy through the mill push button, the pit push button, and the selector switch.

It is to be understood that the aforedescribed electrical circuit has been presented in a simplified form for the purposes of clarity and that various detailed modifications can be incorporated therein by one skilled in the electrical art.

I claim:

1. In combination with a row of spaced soaking pits and a metal rolling mill, an ingot buggy movable along said row to said rolling mill for transferring ingots, an ingot buggy drive system comprising a pair of spaced winches, said winches being positioned, at opposite ends of said row of spaced soaking pits; a first cable having one end attached to one of said winches and its opposite end attached to one end of said ingot buggy; a second cable having one end attached to the other of said winches and its opposite end attached to the opposite end of said ingot buggy; a winch drive mechanism for each of said winches; a pair of motors, each motor being adapted to drive one of said winches through said winch drive mechanism; a pair of electrically controlled brakes, each being connected to one of said winch drives; a common generator system connected to both of said motors to supply electric power to both of said motors simultaneously and control means operatively connected to said generator system for selectively moving and posi-' tioning said ingot buggy, said control means including means for said generator system for governing delivery of greater voltages than a predetermined voltage by said generator system selectively to the armatures of said mo- -pulls on said cables connecting said winches with said ingot buggy so as toefiect selected movement of said ingot buggy in its travel to and between said soaking pits and said metal working mill, said control means including Yfurther means to cause said brakes to efiect a holding action when said motors are deenergized, and said control means also including cam actuated switch means for controlling movement of said buggy between pits and between the pits and said mill including a coarse cam actuated limit switch mechanism for controlling movement of the ingot buggy from pit to pit, and pit to ,mill'; and a vernier cam actuated limit switch mechanism for accurate movement control of said ingot buggy between adjacent pits.

.2. The apparatus of claim 1, wherein said control means includes means providing higher voltages to said motor armatures for selected extensive movements of said buggy than for selected less extensive movements of said buggy for thereby causing said buggy to'travel at higher speed for the more extensive movements of the buggy 16 between the metal working mill and the pits most remote from the mill.

References Cited in the file of this patent UNITED STATES PATENTS 1,139,554 MacLean .May 18, 1915 1,206,576 ,Moss Nov. 28, 1916 1,324,937 Smith Dec. 16, 1919 1,931,107 Dowell Oct. 17, 1933 2,071,168 .Kersting Feb. 16, 1937 2,168,777 McCreary Aug. 8, 1939 2,462,233 Stoltz Feb. 22, 1949 2,472,860 Russell June 14, 1949 2,474,267 Mahnke June 28, 1949 2,508,180 Mahnke et al. May 16, 1950 2,583,078 Auburn Jan. 22, 1952 2,586,412 Winchester Feb. 19, 1952 2,639,336 Woolf May 19, 1953 2,640,113 Becker May 26, 1953 2,715,702 Winchester Aug. 16, 1955 

